Wire and refractory article and method of making the same



Nov. 16,1926. 5 1,607,547

F. S. M CULLOUGH WIRE AND REFRACTORY ARTICLE AND METHOD OF MAKING THESAME Filed July 12. 1926 Patented Nov. 16, 1926.

UNITED STATES PATENT OFFICE.

FREDERICK S. MOCULLOUGH, 0F EDGEWOOD, PENNSYLVANIA.

WIRE AND REFRACTORY ARTICLE AND METHOD OF MAKING THE SAME.

Application filed July 12, 1926. Serial No. 121,852.

This .invention relates to the manufacture of wire and porcelain or likerefractory articles, and constitutes an improvement on the inventiondisclosed in my Patent No. 1,549,591 dated August 11, 1925.

In the manufacture of certain types of electrical devices wherein aheating wire is passed througha body of refractory material, such forinstance as a porcelain body, it has been found that the wire, which isusually of a small diameter, has a relatively short life when it isheated and cooled in its subsequent use.

Various attempts have been made to remedy this difliculty, one methodbeing.disclosed in my co-pending application Serial No. 79,351 filedJanuary 5, 1926. In mysaid co-pending application, I have disclosed amethod wherein the porcelain or other refractory material is appliedunder such conditions that the wire is firmly held in the porcelain, andthe porcelain is in effect shrunk onto the wire.

I have now discovered that the length of life of the wire may be verymaterially increased if the wire does not fit too snugly in theporcelain, so that it may be free to expand and contract therein withoutundue chafing against the body of the refractory.

The nature of the present invention may be readily understood byreference to the accompanying drawing, wherein:

Figure 1 is a diagrammatic view illustrating a wire and porcelainarticle mounted in a vessel'which may be evacuated, and wherein theporcelain or other refractory may be fired.

Figure 2 is an enlarged detail section of a portion of the wire andporcelain article be fore it has been fired.

Figure 3 is a transverse section in the plane of line III-III of Figure2.

,The article includes a rod 5 of porcelain or other refractory or othersuitable refractory which has one or more holes 6 therethrough, througheach of which is passed an electric resistance wire 7. Surrounding theporcelain is a metal shell 8, which is preferably in the form of acomplete metal cylinder, and it is preferably of a magnetic material,such as nickel. This article may be supported by a base or othersupporting means 9. The article after it has been assembled, and beforethe porcelain has been entirely fired, is placed within a vessel ofglass or other suitable material, such vessel being designated 10, andthis vessel may be sealed to the support 9, or otherwise fitted thereto,m such manner as to form an airtight o1nt. Leading from the vessel is atube 11, which is connected to a vacuum and drive out the occulatedgases.

The porcelain, when it is thus heat treated under reduced pressure,tends to 0011-.

tract, so that the holes therein have a tendency to become smaller.According to the present Invention, it is proposed to make the holes atleast one and one-half times as large as the diameter of the wires 7.This will permit the hole to shrink without the porcelain being forcedinto intimate contact with the WlI'eS, so that while the wires aresupported by the body of the refractory, they are sufiiciently free toexpand and contract in their subsequent use without binding and withoutsuch strain or chafing as will result in the disintegration and pullingapart of the heater wire. This insures a long life for the heater orother device constructed in this manner.

The hole is preferably made no larger than substantially one andone-half times the diameter of the wire 7, because if it is made larger,the wire does not receive proper support in the porcelain after theporcelain or other refractory has been heat treated and the heat of thewire is not so effectively transmitted to the body of the refractory, sothat the efficiency of the device as a heater for certain purposes isnot as great as it should be. I do not confine myself to this particularratio between the wire and the raw refractory, as the hole may be madesomewhat greater or less, according to the character of the refractoryand the extent of contact desired between the porcelain and wire in thefinished article.

A particular advantage of the present invention resides in theconstruction of a heater wherein the heater wire may be embedded in amass of porcelain or other refractory and wherein the embedded heaterporcelain rod wherein the diameter of the wire is not subject to unduebinding or chafing sufficient to result in its disintegration, butwherein the wire is fairly well supported in the porcelain or otherrefractory, and wherein heat may be effectively conducted from the wirethrough the refractory.

While I have illustrated a preferred manner of firing the porcelain in avacuum, it will be understood that I- do not limit myself to theparticular method therein disclosed, nor to the use of radio frequencycurrents as a means for heating the wire and porcelain article, and itwill be understood that various changes and modifications may be made inthe construction of the article and the method of' eflecting theinvention within the spirit of my invention and under the scope of theappended claims.

I claim as my invention:

1. The herein described method of manufacturing a wire and porcelainarticle, which consists in passing the wire through a hole in theporcelain which is substantially larger than the diameter of the wire,and then heat treating the porcelain.

2. The herein described method of forming a wire and porcelain articlewhich consists in passing a wire through a hole in a hole issubstantially one and one-half times treating the porcelain in a vacuum.

3. The herein described method of form ing a wire and porcelain articlewhich consists in passing a wire through a hole in a porcelain rodwherein the, diameter of the hole is substantially one and one-halftimes the .diameter of the wire, and then heat treating the porcelainunder a reduced pressure.

4. The herein described method of forming a wire and porcelain article,which consists in passing the wire through a hole in a refractory rodwherein the diameter of the hole is larger than the diameter of the wireso that the wire is loose therein, applying a a metal shell to theoutside of the porcelain, and then heating the porcelain rod and shellin a vacuum by induction to heat treat the porcelain and contract theporcelain about the wire.

5.-A wire and porcelain article of the type described comprising aporcelain rod having a hole therethrough and having a wire passedthrough the hole wherein the wire is loosely received in the hole but issupported by the porcelain.

In testimony whereof 'I have hereunto set my hand.

' FREDERICK s. McCULLOUGH,

